When formed in dies, hollow blow molded plastic articles such as containers or bottles usually have flash in at least one of the shoulder, neck and finish areas. The finish also has material which must be removed to provide an end face for sealing engagement with a closure or cap engageable with the neck of the article.
Various methods and apparatus have been previously used to remove the flash from an article and machine a face on the finish. In these methods, a separate apparatus or machine has been used to perform each step of removing the flash, removing material from the finish, forming a face on the finish, and inspecting the completed article. Conveyors move the articles from one machine to the next and separate transfer mechanisms associated with each machine pickup and load articles into each machine and unload articles from each machine.
In U.S. Pat. No. 4,614,018 there is disclosed a method and apparatus wherein hollow plastic articles to be trimmed are intermittently advanced through a plurality of generally circumferentially spaced stations by a turret carrying vacuum heads engaging the articles. To assure positive and accurate location of the articles in each station each vacuum head picks up and engages an article in a load station and continuously engages the same article throughout all successive stations unless the article is rejected and released prior to the unload station. Preferably, to facilitate processing runs of articles of different sizes, the articles are located and engaged relative to a bottom edge thereof. Preferably, to facilitate loading, unloading and processing of articles in the stations, each vacuum head can be moved to change the orientation of the axis of the article it is carrying from one station to another. When at least two articles could be processed at the same time in a station, the articles are laterally spaced apart when carried by each vacuum head assembly to facilitate processing them in the station. To facilitate changing the cycle time of the trimming apparatus, the turret and the loading and processing equipment in the various stations are all driven by a common variable speed drive. To facilitate processing runs of articles of different sizes, the location of the processing equipment in each station can be varied and adjusted with respect to the position of articles in the station engaged by the vacuum heads.
It has been known that when a simple conveyor is used, significant effort is needed to insure that the bottles are accurately located in each station prior to beginning the operation. The process of locating the bottle causes time loss and uses significant floor space. In addition, the conveyor speed must be relatively slow to prevent tipping of the bottles. The slow speed of the conveyor further limits the speed of the trimming system.
When a more complex apparatus with bottle holding nests is used, the location and speed problems are reduced and less floor spaced is needed. However, this type of conveyor is required a large number of bottle holding nests which require more investment and time for each job change. Such a method and apparatus are shown, for example, in U.S. Pat. No. 4,198,886.
Most bottles are designed to stand on a stable flat base. Because of this it is possible to handle most bottles on a simple conveyor without special tooling. However, empty plastic bottles with flash at the top are difficult to convey standing up because they are very unstable.
Among the objectives of the present invention, are to provide a method and apparatus for positioning and indexing molded hollow plastic articles such as empty plastic bottles which need to be trimmed at the top and moving the articles through successive stations while the articles are in upright position; wherein the articles are held in stable upright position; and wherein complex conveyors including bottle holding nests, vacuum cups and the like are eliminated.
In accordance with the invention, a method and apparatus for positioning and indexing molded hollow plastic articles for trimming molded hollow plastic articles having flash and a finish for a closure; wherein the articles are supported and moved in succession by vacuum conveyor which holds the articles in upright position and moves them past successive stations for deflashing, facing, inspection, rejection and unloading. The conveyor is a chain slat conveyor having longitudinally spaced vertical holes that communicate with a vacuum chamber over which the conveyor is trained. The conveyor is driven intermittently and moves the articles in succession past each of the stations. At the load station, the articles are oriented so that they are in proper alignment and relationship to the openings in the conveyor.